Common types of energy storage devices include batteries and capacitors. Batteries use chemical reactions and traditional capacitors use the physical separation of electrical charges to store energy. In contrast, supercapacitors are high-capacity capacitors that can accept and send charge much faster than batteries and can store much more energy per unit volume than a traditional capacitor.
The structure of a typical supercapacitor includes a separator sandwiched between two electrodes and a liquid electrolyte ionically connecting both electrodes. Although supercapacitors containing a liquid electrolyte have excellent energy storage properties, such supercapacitors lack sufficient mechanical properties. Accordingly, traditional supercapacitors require a structural casing or a separate structural support to provide mechanical characteristics.